FR2690740A1 - Liquid level indicating appts. e.g. for culture container - has transparent rods with conical lower ends at different heights above floor of container, which reflect light back towards source when not immersed in liq. to appear bright, and which appear dark when light is refracted into liq.. - Google Patents

Abstract

The appts. comprises a number of transparent rods (1a,1b,...1n) of different lengths assembled in graded order either in a line or in a circle. The top surface of each rod (2a,2b,...2n) is machined flat allowing light from above to enter the rod. The bottom end of each rod is a cone reflecting light back to the top of the rod if the base is not immersed in liquid. Rods which are immersed in liquid appear dark to the observer while rods not immersed appear bright due to the internally reflected light. USE/ADVANTAGE - Eg for washing machine or dishwasher. Simple, low cost liquid level indication simplifies construction of tanks and liquid containers.

Description

Optical method and device for indicating the level of a liquid contained in a container.

 The present invention relates to an optical method and device for indicating the level of a liquid contained in a container. It also relates to the containers applying this method and this device.

 According to a particularly advantageous application, although in no way limitative, the method and the optical device according to the invention can in particular be used to indicate or measure the volume of water present in the bottom of the pots or culture vessels with water reserve.

 An optical liquid level indicator is known (FR-A-2,451,023), in particular for household appliances such as dishwashers and washing machines, comprising an optical bar which projects from the top into a liquid tank. and comprises, in its upper end section, a planar surface for incidence of light and in its lower end section, an oblique surface reflecting light when it is not immersed in a liquid. In this way, when the lower end of the light bar is not immersed in the liquid, the light rays passing through it from the surface of incidence of the light, are reflected by the oblique surfaces of said lower end and brought back on the surface of incidence which appears bright. On the other hand, when the lower end of the optical rod plunges into the liquid, the light rays passing through it from the surface of incidence of light, are refracted on the oblique surfaces of said lower end and penetrate the Liquid, so that the surface of incidence of the light appears dark and almost black.

 If such a device makes it possible, in principle, to verify the presence or absence of a predetermined minimum quantity of liquid, it does not make it possible to obtain indications on the level of the liquid contained in the container.

 On the other hand, it is often difficult to judge whether the incidence surface shines sufficiently to indicate an absence of liquid or whether it is dark enough to indicate the presence of a satisfactory quantity of said liquid.

 An object of the present invention is therefore to remedy these shortcomings of the optical level indicators of the aforementioned kind.

 According to the invention, this objective is achieved by a method and a device according to which the containers are provided with a plurality of light bars placed in parallel and each having, on the one hand, at their upper part, a surface d incidence or entry surface of the light and, on the other hand, at their lower end, a surface capable of reflecting light, the lower ends of these light bars being arranged offset from one another, preferably according to a regular shift.

 On the other hand, according to another characteristic arrangement of the invention, one of the bars of the set of optical bars is dimensioned and / or arranged so that its lower end provided with a reflecting surface is never immersed in the liquid, this bar thus fulfilling the function of witness having, for example, a length much shorter than that of the other optical bars indicating level.

 When the device equips a container, the upper ends of the light bars are placed visibly, outside of it, and the lower ends of the level indicator light bars are arranged at increasing distances from the bottom of said container.

 It is understood that when the level of the liquid is maximum, the lower ends of all the level indicator light bars are immersed, so that their light incidence surfaces all appear dark. On the other hand, the lower end of the light-indicating rod does not plunge into the liquid, so that its light-entering surface always remains bright and serves as a comparison surface making it possible to know, without possible error of judgment, whether the the light entry surfaces of the level indicator light bars are all bright or all dark. As the liquid level drops, the lower ends of an increasing number of level indicator light bars no longer plunge into said liquid, so that their light incidence surface appears bright.

 By carrying volumetric indications facing the incidence surfaces or light entry surfaces of the light bars of the set of light bars level indicators, it is possible to measure and know the volume of liquid contained in a container , with an accuracy which will depend on the number of light bars included in said set.

In the interesting application to pots or culture tanks with water reserve, the method and the device according to
The invention makes it possible to eliminate the transparent windows which are fitted to these materials and which have the disadvantages of complicating their manufacture and losing their transparency more or less quickly in contact with standing water without it being possible to clean them.

 The manufacture of culture trays or pots equipped or intended to be equipped with the device according to the invention can be simplified and this device can be designed and arranged so that it can be easily removed from the trays or pots. In order to clean them, for example to rid it of the deposit of microscopic algae which forms over time on the surfaces in contact with the culture water.

According to another characteristic arrangement of
The invention, the light bars are connected to each other, laterally, without a solution of continuity, so as to form a conduit through which the liquid can be introduced into the container.

The above objects, features and advantages, and others, will become more apparent from the following description and the accompanying drawings in which
Figure 1 is a front view of a first embodiment of the optical level indicator device according to
The invention.

 Figure 2 is a top view of this device.

 Figure 3 is a partial view, in cross section and on a larger scale of a set of transparent bars assembled by connecting tabs.

Figures 4 and 5 are respectively front and plan views, on a larger scale, illustrating an example of implementation of the method and the device according to
The invention, FIG. 4 being a sectional view along line 4-4 of FIG. 5.

Figures 6 and 7 are views comparable to Figures 4 and 5 and illustrating a culture tank with water reserve equipped with a level indicator device according to
The invention, comprising an optical witness bar.

 Figure 8 is a front view of another embodiment of the device of the invention.

 Figure 9 is a side view of Figure 6.

 Figure 10 is a perspective view of a third embodiment of the optical level indicator device according to the invention.

 Figure 11 is a plan view of this device.

 Reference is made to said drawings to describe interesting examples of implementation of the method and embodiment of the device according to the invention.

Reference is made, in the remainder of this presentation, to a more particularly advantageous application of this process and of this device to the indication or measurement of the level of the water contained in the water reserve of the tubs or pots. culture, but it is also emphasized that the invention is not limited to this application and that it can be applied to
Indication or measurement of the level of different liquids contained in containers of various kinds.

The optical liquid level indication device according to the invention is remarkable in that it comprises a plurality of light conducting optical bars la, lb, îc, 1d, ..., 1n, preferably placed in parallel and each having, on the one hand, at their upper part, an incidence surface or light entry surface 2a, Zb, 2c, 2d, ..., 2n, and, on the other hand, their lower end, a light-reflecting surface 3a, 3b, 3c, 3d, ..., 3n, the lower ends of these light bars being arranged offset from one another, preferably according to a regular offset, corresponding to an increasing or decreasing arithmetic progression, depending on whether one considers
The lowest end la or The highest end ln.

 According to another characteristic arrangement of the method and the device of the invention, one of the light bars of the set of light bars is dimensioned and / or arranged so that its lower end is never immersed in the liquid. This lx bar has, for example, a much shorter length than that of the other optical bars la, lb, lc, ld (FIG. 6).

 The set of light bars according to the invention can be made of any suitable transparent material, rigid or flexible, such as glass, polymethyl methacrylate, polycarbonate, crystal polystyrene or the like. This transparent material can be colorless or Slightly tinted.

 The transparent bars la, lb, lc, ld, ..., ln, lx, may be straight or not. They can have a circular, or square, or other section. They can be entirely executed in the same material or include a core of highly refractive transparent material coated in a transparent material of lower index to allow the total reflection of light on the separation surface of the two transparent materials.

 The upper ends of the bars provided with the light entry surfaces 2a, 2b, 2c, 2d, ..., 2n, 2x, are preferably arranged at the same level, for practical reasons, but they can just as easily well be placed at different levels, the important thing is that their lower ends provided with reflective surfaces are arranged at levels offset from each other.

 The light entry surfaces 2a, 2b, 2c, 2d, ..., zone, 2x, are preferably planar, but they can also be convex, or oblique (FIGS. 8 and 9) presenting, in this case , an inclination of 45 degrees relative to the axis of the bar.

 When the transparent bars la, lb, lc, ld, ln, lx, are executed with a circular section, their lower end 3a, 3b, 3c, 3d, ..., 3n, 3x, has the shape of a cone of revolution or right circular cone whose generatrices form an angle of about 45 degrees relative to the axis of the bars. The reflective surfaces formed by the lateral surface of this cone of revolution therefore have an inclination of approximately 45 degrees relative to the axis of the bars.

 When the transparent bars have a square or rectangular section, their lower end may have the shape of a prism with total reflection oriented to return the light beam parallel to itself, or comprise, on its flat face oriented parallel to the axis bars, a coating constituting a plane mirror making it possible to return said light beam towards the surface inclined at 45 degrees making it possible to reflect the latter either towards said lower plane mirror, or towards the upper entry surface (FR-A-2.394 .069).

The set of transparent bars can be constituted by elements executed individually and then assembled by any suitable method or means, or mounted on a common support; it can also advantageously be formed in one piece by any process (molding, extrusion and machining, etc.), each bar being connected laterally to at least one neighboring bar by a longitudinal tab of
Connection 4 of small width and thickness. The connecting tongues 4 can advantageously include longitudinal grooves offset 4a on their opposite faces, or similar interruptions, so as to create a solution of continuity between the different bars opposing the passage of light rays from one light bar to another .

 As shown in FIGS. 8 and 9, the set of transparent bars can be provided, in its upper part, with a hooking means 5 which can be constituted by a large hook formed in one piece with said set and allowing the attachment of the latter on the upper edge of a container, for example on the upper edge of the chimney 6 which equips the pots or culture vessels 7 with water reserve, for the introduction of water into said pots or tubs.

 The operation of the device and the implementation of the optical method for indicating the level of liquid according to the invention are clearly understood, which is described first with reference, by way of example, to FIGS. 4 and 5.

The set of transparent bars 1a, 1b, 1c, 1d, is housed or pressed into the container 7 so that - on the one hand, its upper end provided with light entry surfaces 2a, 2b, 2c, 2d , protrudes or is visible from the top of the container; - on the other hand, its lower part plunges into the part of the container which is intended to receive the liquid and is disposed at a more or less reduced distance from the bottom 8 of said container 7, according to the appLications
In the application to the indication of the level of water contained in pots or culture tanks with water reserve, the lowest part of the set of bars constituted by the lower end of one of the bars (bar 1a), is disposed at a short distance from the bottom 8, while the intervals separating said bottom from the lower end of the other bars 2b, 2c, Zd, gradually increase.

 FIGS. 4 and 5 illustrate a situation in which the level N of the liquid L contained in the container 7 has fallen below the maximum level, so that the lower ends of certain bars (bars 1a, 1b) are still immersed in the liquid, while the lower ends of the other bars (bars lc, 1d) are no longer.

 The light rays R which enter through the light entry surfaces 2c, 2d, in the light bars lc, ld, the lower ends of which are not immersed in the liquid L, pass through said bars longitudinally and are then reflected by the surfaces reflecting 3c, 3d, which successively inflict two 90-degree deflections on them so that they are brought back to the light-entering surfaces 2c, 2d which appear bright.

 On the other hand, the light rays R 'which enter, through the light entry surfaces 2a, 2b, into the light bars 1a, 1b whose lower ends are immersed in the liquid L, pass through said bars longitudinally and are refracted in the liquid L when they pass through the separation surface between the oblique surfaces 3a, 3b, of the lower ends of the bars and the said liquid. Given the absence of reflection of the light rays R ′, the light entry surfaces 2a, 2b appear dark, almost black.

When the level of the liquid drops, it is the light entry surface 2b of the optical bar 1b which will also appear shiny when the lower end of said bar no longer immerses in the liquid, in application of the phenomenon described above, and and so on. When the container no longer contains liquid or only a very small amount thereof, the light entry surfaces 2a, 2b, 2c, 2d, ..., 2n, of all light bars la, lb, lc , Id, ..., ln, appear bright, while When the container is full, the light-entering surfaces of all the light bars appear dark.

 It is understood that by wearing volumetric marks (such as 1/10, 4/10, 7/10, 10/10: FIG. 7) opposite the light entry surfaces 2a, 2b, 2c, 2d, .. ., 2n of the different light bars la, lb, lc, ld, ..., ln, (figure 5), it is possible to obtain a fairly precise indication of the level of the liquid contained in the containers such as the pots or culture tanks with water reserve.

According to FIG. 6, the set of light bars comprises a plurality of level indicator bars 1a, 1b, 1c, 1d and a witness bar lx of significantly shorter length, and this set is designed and mounted on a tank or pot. of culture 7 to reserve of water 9, so that
The lower end 3x of this indicator rod lx is disposed above and at a distance from the maximum level N ′ of the water that can be contained in said water reserve, which is determined by the situation of the horizontal grid 10 which delimits the volumes intended to receive the soil and the culture water respectively, so that said lower end 3x is never immersed in water.

 The indicator bar lx has, like the level indicator bars la, lb, lc, Id, an upper end provided with a 2x light entry surface and a lower end provided with a reflective surface 3x. In view of the fact that its lower end never plunges into the liquid, the light rays R which enter through its light entry surface 2x are always reflected, by its reflecting surface 3x, in the direction of said light entry surface This permanently shiny surface 3x serves as a witness allowing to judge, without risk of error, if the light entry surfaces 2a, 2b, 2c, 2d of the other light bars la, lb, lc, ld , are bright or dark.

According to another characteristic arrangement of
The invention, the light bars la, lb, lc, ld, ..., ln, are connected to each other, laterally, without a solution of continuity, so as to form a hollow cylinder (Figures 10 and 11) which can be used to form the conduit through which the Liquid can be introduced into the container. For example, in the application to pots or culture tanks with water reserve, the set of light bars produced in the form of a hollow cylinder can replace the traditional chimney by which water is introduced into said pots or tanks.

Claims (12)

1. - Optical method for indicating the level of a liquid contained in a container, characterized in that an assembly made up of a plurality of light bars (la, lb, lc, ld,. .., ln) each comprising, on the one hand, at their upper part, a light entry surface (2a, Zb, 2c, 2d, ..., 2n) and, on the other hand, their lower end, a reflecting surface (3a, 3b, 3c, 3d, ..., 3n) capable of reflecting light in the direction of said entry surface, and the lower ends of the different light bars of which are offset relative to each other, so that the light bars (lc, ld) whose lower ends (3c, 3d) are not immersed in the liquid (L) allow a reflection of light towards their entry surface of light (2c, 2d) which appears bright, while the bars (la, lb) whose lower ends (3a , 3b) immerse in the liquid allow refraction of the light in said liquid, so that their light-entering surface appears dark.  2. - Method according to claim 1, characterized in that one (lux) of the light bars of the set of light bars (la, lb, lc, ld, ..., ln) is dimensioned and / or arranged in such a way that its reflecting end (3x) is never immersed in the liquid, so that this bar fulfills the function of a witness permanently exhibiting a bright (2x) light entry surface. 3. - Optical device indicating the level of a liquid contained in a container, characterized in that it is essentially constituted by a plurality of light bars (la, lb, lc, ld, ..., ln) comprising, each , on the one hand, at their upper part, a light entry surface (2a, 2b, 2c, 2d, ..., 2n) and, on the other hand, at their lower end a reflecting surface (3a , 3b, 3c, 3d, ..., 3n) able to reflect light towards Said entry surface, the ends of the various light bars being arranged offset from one another. 4. - optical level indicator device, according to claim 3, characterized in that it comprises an optical bar (lux) of much shorter length than those of other level indicator optical bars (la, lb, lc, ld) , this shorter optical bar being intended to serve as a witness. 5. - optical level indicator device according to one of claims 3 or 4, characterized in that the set of light bars (la, lb, lc, ld, ..., ln, lx) is formed of a single piece, the different light bars constituting said assembly being assembled to each other, laterally, by means of longitudinal connecting tongues (4). 6. - optical device indicating the level of a liquid contained in a container, according to any one of claims 3 to 5, characterized in that the light bars (la, lb, lc, ld, ..., ln) are connected to each other, laterally, with no continuity, so as to form a hollow cylinder which can be used to form the conduit through which the liquid can be introduced into the container. 7. - optical level indicator device according to any one of claims 3 to 6, characterized in that the offset of the lower ends (3a, 3b, 3c, 3d, 3n) of the level indicator optical bars (la, lb, lc, Id, ..., 1n) corresponds to an arithmetic progression. 8. - optical level indicator device according to any one of claims 3 to 7, characterized in that the light bars (la, lb, lc, ld, ..., ln) have a circular section and in that their lower end (3a, 3b, 3c, 3d, ..., 3n) has the shape of a straight circular cone whose generatrices form an angle of about 45 degrees relative to the axis of said bars. 9. - optical device level indicator according to any one of claims 3 to 8, characterized in that The set of transparent light bars (la, lb, lc, ld, ..., ln) is provided, in its upper part, with a hooking means (5). 10. - Container, for example pot or culture tank with water reserve, characterized in that it is equipped with a level indicator device according to any one of claims 3 to 9. 11. - Container constituted by a pot or culture tank with water reserve, according to claim 10, characterized in that the witness optical bar (six) is dimensioned or arranged so that its reflecting surface (3x) is placed above and at a distance from the maximum filling level (N ') of the water reserve. 12.- container according to one of claims 10 or 11, characterized in that it is provided with volumetric marks, facing, the light entry surfaces (2a, 2b, 2c, 2d) of the various light bars ( la, lb, lc, 1d).